The Concrete Block Calculator estimates how many cinder blocks you need to build a wall — a must-have step before buying materials for any masonry project. Enter your wall length, wall height, and block size to get the total blocks needed and mortar bags required. Add your price per block and price per mortar bag to also see your total material cost and wall area.
Blocks Needed
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Mortar Bags
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Wall Area
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Total Material Cost
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The number of blocks depends on your wall dimensions and block size. Calculate wall area (length × height) and divide by the coverage area of one block. Standard 8"×8"×16" blocks cover approximately 0.89 square feet each.
Convert square meters to square feet (10 sq m = 107.6 sq ft), then divide by the block coverage area. For standard blocks covering 0.89 sq ft each, you'd need approximately 121 blocks.
Generally, you need one bag of mortar for every 33-35 blocks. This accounts for the mortar joints between blocks. Our calculator estimates mortar bags based on this standard ratio.
Nominal size includes mortar joints, while actual size is the physical block dimension. An 8"×8"×16" nominal block is actually 7⅝"×7⅝"×15⅝" to account for ⅜" mortar joints.
Material costs vary by location but typically range from $3-8 per square foot for blocks and mortar. Labor costs add $10-20 per square foot. Our calculator helps estimate material costs based on current prices.
Yes, it's recommended to add 5-10% extra blocks to account for cutting waste, breakage, and future repairs. This ensures you have enough materials to complete your project.
Essential tools include a trowel, level, string line, rubber mallet, chisel, safety glasses, and a mixer for mortar. A block splitter or masonry saw helps with cutting blocks to size.